1. Field of the Invention
The invention relates to a polypeptide, a nucleotide sequence thereof, and a method for using the same for preventing DNA synthesis and inhibiting cell proliferation.
2. Description of the Related Art
With the disclosure of signaling transduction pathways, more and more tumor-targeting drugs have been developed. And some of them have been successfully applied in clinic and gotten good effects. For example, the protein BCR-ABL expressed in many leukemia cells, which has relatively strong protein kinase activity and plays an important role in the occurrence and development of leukemia. Through studying the structure of protein BCR-ABL, many compounds that can specifically inhibit the biological activity of protein BCR-ABL are designed and produced, for example, Glivec is used in treatment for leukemia.
Cell growth signals are transmitted to cell nucleus by growth-promoting factors inside and outside cells via a series of proteins, bringing about the change of structure and function of many regulatory cyclins and leading to cell division. Among these proteins regulating cell cycle, proliferating cell nuclear antigen (PCNA) plays a significant role. DNA replication fork is the key protein complex of DNA synthesis in DNA replication. PCNA is a composition of DNA replication fork complex and can bind DNA and many kinds of proteins, especially the DNA polymerase necessary for DNA replication, which facilitates DNA polymerase to synthesize new DNA chains. PCNA exists in all dividing cells. Because of PCNA's vital function in cell cycle, to block its biological function in cell cycle is a means to develop new drugs for treatment of tumor and other diseases resulting from abnormal cell proliferation. Till up to now, as the mechanism that PCNA takes part in cell cycle regulation is unknown, there is no useful method or compound that can directly block the biological function of PCNA to inhibit cell proliferation.